U1800 duramax. Customer: My 2004 Silverado Duramax blew the EDM fuse.

U1800 duramax. The U1800 code indicates communication loss with the engine control module (ECM). After replacing LB7 injectors, check the U1800 injector driver module and wiring harness for damage or loose connections. The U1800 code indicates the Fuel Injection Control Module (FICM) is not communicating properly. It took some digging, but mine was in a different spot Duramax often faces crank no start due to low FICM voltage and communication errors like DTC U1800. It is usually a fairly robust module. LB7 & U1800 no start after replacing the injectors. The fuel injector harness has a rubbing issue and then the connectors coming loose. Then crank, crank, crank and finally it starts up but no smoke or anything at Feb 8, 2010 · Now I scanned for codes and I get U1800 and P0090 then I erase the codes and scanned again and it came up with U1800 and P0090 again. I replaced the fuel filter housing as well and it primes up good and hard. The code indicates that the theft deterrent signal is out of specification, which is a common issue with GM Passlock systems. Truck now has rail pressure, rpms show up on the scan tool, good lift pump pressure from the lift pump. Its a diesel there r no spark plugs. 2L Diesel Engine Duramax Third Generation: 2006-2007. I am also now showing code p0090 which comes back to a faulty fuel circuit from what I have read on here it could be the fpr I replaced that fpr and she will still just crank but not fire. The U1800, U2104, and U2106 codes indicate communication errors between the transmission control module and engine control module. Apr 30, 2025 · Jestem nowy w tym miejscu i mam problem z rozruchem. Aug 23, 2023 · Getting a p0090 and u1800. The U1800 diagnostic trouble code indicates that there is a communication issue between the vehicle's engine control module (ECM) and the fuel injector control module (FICM). No start can result from faulty injector driver signals or poor ground. could be the wiring causing both Customer: I'm experiencing issues with a U1800 and P0090 code on my 2001 Duramax with the LB7. Has the computer or FICM failed? Background: code PO 0090 had tripped and Truck would not start until code was cleared. I read dtc codes and had: P0090 Fuel Pressure Regulator Circuit P0201 P0204 P0206 P0207 P1261 U1800 I cleared the codes & still no start. got u1800 code and 0193 code and Feb 2, 2007 · HELP!! I'M STRESSED OUT!!! I am having problem with my '02 GMC Duramax, It won't start up at all!! At first, I had an Edge juice with attitude on it so i disconnected it and put stock harness in to the same place. Low voltage at the Fuel Injection Control Module (FICM) can cause crank no start. 8M posts 227K members Since 2005 Home Forums Chevy / GMC Duramax 01-04. Apr 30, 2025 · Chevy and GMC Duramax Diesel Forum 3. My tuner says code u1800 I checked fuses and connection on my ficm all are good could it of shorted my ficm out? Jul 14, 2017 · Codes will not clear/erase. La verificación preliminar del cableado y los fusibles no reveló nada, pero no tengo energía en el pin 118 Voltaje de Customer: I own a 2004 Chevy Silverado 2500HD Duramax that occasionally fails to start and displays a U1800 code intermittently. Even after replacing the FICM, no-start issues can persist due to low FICM voltage or wiring faults. You also need to Dec 19, 2016 · The other night I went to drive my 2003 Chevy Silverado 2500HD Duramax which I didn't drive the day before so it was just sitting for only a day. The other modules are trying to talk to it, but it is not responding. Mechanic's Assistant: Are you repairing your Silverado yourself? What have you Apr 21, 2019 · Hi all hoping for some diagnostic help with my LB7. The U1800 GMC code indicates that the vehicle's engine control module (ECM) has lost communication with the fuel injector control module (FICM). . All was fine. Check wiring harnesses and connectors for damage or corrosion. Check the fuses if you have not already done so. May 21, 2017 · Vehicle: 2003 GMC ECSB 4x4, LB7/Allison, 241,000Miles, Only mods PPE Economy Tuner, MBRP 4" Turbo Back Problem: Won't Start! Throwing P0090, U1800 codes and a bunch of others. This Duramax was towed in for a cranks no start condition. I replaced cp3. When I checked the fuse box the #1 25amp fuse labeled INJ was blown. I had just washed the truck a few hours before. Eine vorläufige Überprüfung der Verkabelung und Sicherungen ergab nichts, aber ich habe Jan 23, 2018 · 223000 millas sin problemas eléctricos, pero a mitad de camino de la entrada hoy se apagó y se negó a arrancar. Jan 3, 2017 · So did your filter head rebuild solve your fuel leak? You never said if your machanic got your truck started but just got a code? Does it start at all now? U0105 is this your code? Code: U0105 Modules: ECM, TCM Description: Lost Communication With Fuel Injector Control Module (FICM) Or give us your codes would really help so we're not doing the guessing game. 5-2005 (LLY) 6. Code U1800 indicates a communication fault between the engine control unit (ECU) and other modules. truck has 93k on it but extremely high hours almost 5000 (mine with 250k only has like 6500 Jul 17, 2016 · Truck remained running and didn't throw a code. My scanner gave me these stored codes U1800, P0090, P0089, and P0404. We would like to show you a description here but the site won’t allow us. CRANK Fuse 10 Amp PCM 1 Fuse 10 Amp PCM B Fuse 20 Amp ECMRPV Fuse 15 Amp The GROUNDS are S103 & G103 for the ECM. A couple of weeks ago i had the MIL come on. This where we have a no start and has no voltage to injectors. Mechanic's Assistant: Have you checked the engine's fuel supply? Jan 28, 2019 · Need some help on my problem,was washing my engine and it died on me now won't start. I recently replaced the FICM and fuel filter, and while it was running, it suddenly lost power and won't start. History Electronic Control Module (ECM) DTC P0370, U1800, B2960. U1800 code GMC Duramax P0090 as well, 04 Chevy 2500 lb7, I just replaced the engine and it won't start. codes U2106, and P0700. Everything was fine before i changed the pump any ideas what Apr 1, 2021 · Some codes that came up included u1800, p0090, p0193,p0380, p0540. Conditions for Setting the DTCThe ECM detects a circuit fault related to the high voltage circuit to cylinders 2, 3, 5, and 8. Thanks in advance guys. Does AllData provide this type of info? Aug 26, 2018 · Reason I bring that up is I now have a code u1800 which comes back to the ficm. U1800 and a few other No start. That's when I realized this was the same shit that happened 6-8 months ago. Customer: My 2004 Silverado Duramax blew the EDM fuse. On my tech 2 desired is set around 5800psi? Dec 16, 2014 · major 911 issue. doc*TABLES. Nov 22, 2024 · Just finished installing a new cp3 everything is plugged in and ready to go but when i hooked up the scanner it gave me a u1800 code. Occasionally the truck will start and run Got a 03 lb7 with a U1800 code. It gives code U1800 - Answered by a verified Chevy Mechanic Jan 23, 2018 · 223000 Meilen ohne elektrische Probleme, aber heute auf halbem Weg aus der Einfahrt schaltete er sich ab und weigerte sich zu starten. See where the fuel pressure is going? Usually the def fluid will cause the fuel injectors seals to leak!The U1800 is a loss of communication code with the transfer case control module! Apr 3, 2016 · A forum community dedicated to Chevy and GMC Duramax diesel owners and enthusiasts. 5L Diesel Engine Duramax First Generation: 2001-2004 (LB7) Duramax Second Generation: 2004. It was driven home Hello and thank you for using Just Answer! I am sorry to hear that you are experiencing car issues. I have not seen too many FICMs fail due to water. I can delete Dec 4, 2015 · bigbopper Member Mar 15, 2009 60 0 6 anderson sc Dec 4, 2015 #1 code u1800 lost commuication with ficm ? what can I check . You need to verify all the fuses that send power the ECM. Fuel system had lost prime due to a leak on the suction line betwee Well def fluid and is bad it can cause lots of problems in the fuel system. Oct 12, 2014 · Engine still turns over but wont start and U1800 code came up again. The code came back as U1800. Recently my #6 injector started knocking/rattling under load Jun 15, 2018 · Ok after fooling with more I finally got a U1800 loss of communication with ficm tested all fuse they ok. For a crank no start, check the camshaft and crankshaft position sensors first, as faulty signals prevent ignition. Feb 11, 2024 · u1800 sounds like a wiring issue look up the common spots for these to go bad. Check battery health and wiring harness for corrosion or damage. 6 Duramax U1800 Code FICM Not Responding Duramax engines often face FICM failures causing crank no start and intermittent power loss issues. DTC U2104 CAN Bus Sep 8, 2007 · U1800 Modules:Description: Lost Communications With Fuel Injector Control Module (FICM) Maybe a harness issue? Sure there was a C after it? At the top of the forum page is a sticky for DTC look up codes. Sep 28, 2017 · I hear what I believe a sound indicating continuous power going to the fuel pressure regulator or fuel pump. No Codes related to the issue. I've seen threads on wire chafes at the ALT bracket and under the fuse center, as well as contamination in the bail connectors. Brand new batteries and alternator but the red battery lamp is still on and after I try to start it I’ll get a u1800 and p0090. This was preventing programming and the no crank. When i - Answered by a verified Chevy Mechanic May 7, 2016 · It is a crank no start condition, with 2 codes that have come up, a P0090 (fuel pressure regulator) and U1800 (ficm - no communication). progressed to spraying either cold and no start hot now no start with either hot/ cold anything. Is the FICM faulty? Mechanic's Assistant: Do all the fuses have the correct amperage for the circuits they are in? Customer: Yes. Code will not clear Mar 7, 2017 · I had an issue blowing the 25A FCIM fuse. Mar 7, 2017 · LB7 code U1800 FCIM blows fuses - solved Jump to Latest 7. What does the U1000 Duramax code mean? It means class 2 communication fault conditions. I shot starting fluid in it just see & it did fire off but immediately died. It was cold that night about 20 degrees. It cranks fine but no start. The FICM is responsible for controlling the fuel injectors, which are crucial components in the fuel delivery system of the vehicle. Wouldn't restart so, I let set awhile & tried to start it, cranks no start. Then on my way home the cel light came on and I looked through my cts2 and it has a bunch of communication codes, p0700, u1000, u1800, u2104,u2106, u2105. Preliminary check on the wiring and fuses revealed nothing, but I don't have power on pin 118 Injector supply voltage at the FICM. Initially It came in with no rail pressure. When I got home I ran the codes. Found no fuses. Anyone have test procedure for U1800 code? Jan 19, 2024 · The U1800 doesn't necessarily mean that the "bus" isn't functioning. It would crank but no start. Tengo un código u1800 por falta de comunicación entre ecm y ficm. Feb 15, 2020 · A forum community dedicated to Chevy and GMC Duramax diesel owners and enthusiasts. Znajduję się w północnym Austin i zastanawiam się, czy ktoś byłby skłonny pomóc w pożyczeniu FICM, jeśli wiązka przewodów nie jest gdzieś przetarta. The only code I'm getting is a p0090 something with the fuel pressure regulator. The other night the truck started ok and ran for a few seconds but then died and hasn't restarted since. Aug 13, 2008 · Ran U1800 diag by SI 2000 and it lead to a FICM which did not change a thing (and I figured that would be the case. 2500HD Duramax often faces intermittent U1800 code and crank no start due to sensor or wiring faults. There is a short that is causing a comm failure with the FICM. Oct 3, 2011 · pulled the code off my edge insight, gave me code u1800. Code PO 0090 would not clear after multiple attempts to clear and U1800 appeared on scanner. Nov 6, 2011 · The U1800 means the FICM is not sending out its state of health message. If I pull the ignition relay in the main fusebox it stops. I checked all the basics first and then put a scan tool on it . Come join the discussion about modifications, towing, classifieds, troubleshooting, maintenance, and more! U1800 GMC Diagnostic Trouble Code (DTC) Definition, Causes and Diagnosis I have a 2003 LB7 Duramax. NOTHING! Can't even find a hint of a wire rubbing or shorting on something. Truck has 95,000 miles on it and is for the most part stock. Any ideas?? Apr 30, 2025 · U1800 keine Kommunikation mit FICM 04 LB7 See Original Jump to Latest 41 views 2 replies 2 participants last post by Mb01rt Apr 30, 2025 Customer: 2002 Duramax truck throwing codes: P0380, P0107, P0118, and U1800 how do I troubleshoot the cause of these? And is there a diagram for the FICM connector pins/wiring harnessJust happened after new injectors and a new fuel pressure regulator installed. Replaced the head gasket, machined the heads, resealed cups, and put it back together. 5 (LBZ & LLY) Apr 8, 2015 · Hi guys after a bit of help diagnosing my truck, getting a u1800 code that I can't get to bottom of. The Crankshaft Sensor, and Camshaft Sensor are connected to the ECM. Air leak, low pressure supply line Fuel injector/s Scanner giving wrong codes * A vehicle with the same engine as the one you selected, plus or minus two years. The engine is completely stock! 2003 Chevy 4500 6. Jan 15, 2014 · has anyone had this code? i posted on here a while ago about my truck crank but no start its been down for 2 months now from what i can find the U1800 is a loss of communication from ECM to FICM have swapped out both with no results. replaced injector now won't start. 2003 Duramax U1800 Code: Crank No Start Diagnostic Guide Duramax engines often face crank no start due to fuel delivery or sensor-related issues. May 4, 2025 · So I've been reading threads for a while now just decided to finally just ask so I got a 02 LB7 the dude I got it from said since he has owned it it never started on its own needed starting fluid (glow plugs were disconnected supposedly) well he has a mechanical fuel pump in the back in the tank 02 duramax P0107, P0540 and U1800 cleared codes they come right back when engine is started in cold weather. These faults can cause delayed or harsh shifting at high RPMs. ) I ran both continuity test and voltage drop test on the power and ground to the FICM, no problem identified. The power to it is constant and eventually drains the battery. May 2, 2010 · I can't seem to resolve an issue I'm having with my 03 2500HD Duramax transmission/electronics and I hope someone has seen AND resolved this before. Wiring is typically the root cause of may problems. Replaced the FPR, low pressure side hoses and I also have a Airdog so I’m almost positive it’s something electrical. Dec 20, 2011 · I have a 2001 Chevy Duramax at my shop. 2003 Chevy Silverado Duramax U1800 Code and No Start Issue Silverado Duramax models often face crank no start issues and ECU communication errors like code U1800. Mar 4, 2020 · My 03 Duramax just died/quit going down the road today just like you switched the key off. The spur gear pump creates about 5 inches of vacuum to draw fuel from the tank, where it first passes under the Fuel Injector Control Module (FICM). I am thinking I fried the FICM but wonder why it took so long for the truck to die after power washing. Did i short out The U1800 diagnostic trouble code indicates that there is a communication issue between the vehicle's engine control module (ECM) and the fuel injector control module (FICM). And if you have a used FICM for sale and thats what I need, please PM me i dont really feel like paying that much for a new one. It certainly could mean that but what it really means is that the ECM is polling the FICM and no one is answering. Failure to communicate with fuel Feb 9, 2020 · So the truck will throw the u1800 code at random I've checked all the grounds swapped the ficm e. c etc Previous owner said problem started after he got the tune put on thr truck. IAH relays check ok. It's throwing codes P1226, P1229, P1235, and P1244, along with a U1800. ? I have a crank no start with code U1800 LB7 Duramax injector harness. I just had my first no-start issue. Check FICM wiring harness for corrosion or damage. I have ground but am not getting power, and even if I disconnect the ECM, it still receives a very mild ground signal from the FICM. I replaced it, but now it's only running on four cylinders. I'm pretty resourceful when I comes to mechanical work, and most electrical stuff, But I need some help trying to track down either a short or determining if the ficm is bad. What exactly does this mean? Is this something that needs to Jan 27, 2019 · My 03 lb7 died during washing my engine my tuner said code u1800 checked my ficm plugs blew them out and checked all fuses but not sure where the relay is for it or fuse,look for chaffed wires nothing tho any ideas. Your machanic can test your FICM Oct 4, 2010 · a buddy has an 04 lb7. Anyways, I primed it still no start, checked fuses and everything, finally it threw a u1800 code. A few Duramax forums said it The codes are U1800, U2106, P0090, P0193, C0227, and C0225. Inspect FICM power and ground circuits using a multimeter. Pulled code and it is U1800. I called for a tow but tried to start it 20 minutes later and fired up fine and has started fine at least a dozen times since the no-start. 5 LB7 Duramax Powertrain Found circuit from ECM 1 fuse to pin 21 of connector 2 at ECM corroded open. Jan 26, 2017 · Hi everyone, Im Dan from sweden and i have a 2003 chevy D-max 4x4. Has new ECM, FICM and all wiring check all powers and grounds good. When the sensor malfunctions, it typically requires a replacement of the ignition switch housing. I start digging into the FICM harness again and this time I cut it all loose all the way back past the alternator. I was in a rush so I just took my other car. Trans gauge not working, speedometer not working, brake light on, abs light, limp mode, no indicator line for PRND, big clunk when moving from R to D. Help … read more I have an 04 Duramax. Nov 20, 2017 · Diagnostic challenges with a GM Duramax: Limp mode, fuel injectors, and the complexities of modern automotive technology. All 3 fuse blocks and looked at under wiring of fuses under hood and inside door jamb. I installed a new modded pump from II, and a new rail psi sensor. 2001 chevy Mechanic's Assistant chat Customer: I have a crank no start issue with code U1800 on my LB7 Duramax injector harness. Manhandling the harness would usually cause the fault to disappear. Is there a circuit I can test to pinpoint the issue? Jun 6, 2004 · A code was indicated U1800 Lost communication with fuel injection control module andU2104 which indicated Can bus reset counter overrun. Truck was purchased not running and previous owner says it just Apr 6, 2015 · It appears to be a problem with +12 VDC, Bad Ground, or Sensor (s), according to the DTC0370, U1800, & P1550 DTC's. Sep 20, 2005 · I recently got the check engine light, and went to Auto Zone to get the code. its better if you just go ahead and open up the whole harness from the alternator area to the ficm. I did a search here in the forums, and found out that it means Loss Of Communications with Fuel Injector Control Module (FICM). Injectors (Bosch) 6 months old. t. It cranked strong but didn’t fire up at all, no sputtering or attempts of starting at all. : george May 25, 2013 · •DTC U1800, or U2104 are not set. Check the EDU fuse and relay for continuity and proper function. The truck started up and then died right away. Dec 8, 2008 · So I just purchased this truck and drove it 1200 miles home. May 17, 2007 · I'm getting: U2104 CAN Bus Reset Counter Overrun U2105 ECS Comm lost U1800 FICM comm loss U1152 HVAC Comm loss U2106 TCS comm loss I've reseated all appropriate fuses and cables. Visually check to see if there is any chaffing, rubbing, along the fuel injector harness. The U1800 code indicates communication issues between the engine control module (ECM) and other modules. Microsoft Word - 2002file8. My buddy hooked up jumper cables and it fired right Dec 11, 2007 · In comparison, the Duramax also uses a two-stage fuel pump, but rather than utilizing a diaphragm-type pump for lift, a pair of spur gears is used to bring fuel from the supply. The troubleshooting flow chart says that if both of these codes come up together, to go straight to the ficm. The fuel injection control module could also be not responding. i had a similar issue, first i found one area by the alternator that was bad then some months passed and it did it again so i kept searching and found more shaffed wires by the ficm. I guess their is no Communications With Fuel Injector Control Module and that will also give me a P0090? Where is the Fuel Injector Control Module located is it on top of the pass valve cover? Jun 13, 2021 · Read the codes U1800, P1226 and google them and start reading. I am here to assist you with your questions. Apr 30, 2025 · U1800 no communication with ficm 04 lb7 Jump to Latest 41 views 2 replies 2 participants last post by Mb01rt 11h ago M Jan 6, 2015 · I have a 2003 Duramax with similar problems. (yes relearned the security thing) we have changed Sep 9, 2008 · U1800 "Lost Communications With FICM" What do you have done to your truck? try filling out a signature My truck is stock except for the lift and tires. originally it would start hard cold and the not restart hot. Replaced Ficm with a known good unit and still no start. This code is set when the engine control module cannot communicate with a series of modules or just a module Nov 30, 2021 · Got codes pulled (p0380, u1800, u2104, u2106, u1301, u1000, u1016) have been looking through all the wiring and fuses. Backstory: Drove down approximately 7 Miles of extremely washboarded dirt road to get to my mother in laws house I have a 2002 Chevy Duramax k2500 that will not start after replacing the alternator. Cleared codes, current DTC U1800. Ich habe einen Code u1800 für keine Kommunikation zwischen ECM und FICM. Feb 28, 2021 · Has anyone ever replaced their BCM with a known good used one and were able to relearn the pass lock code. I swapped the May 6, 2023 · Hey guys, i splashed some water on my FICM while truck was running & it died immediately. 5 LB7 Forums 01-04. P0700 is the tranny telling the computer there is a problem and needs the TCM to be read by a tech 2. The engine started after pumping the primer on the fuel filter housing. Mar 2, 2025 · Strong crank just wouldn’t fire. IGN 0 Fuse 10Amp. You are gonna have preform a return test and measure the fuel return. Dec 14, 2010 · Have a 04 LLY Duramax that I cannot get too start up. Pulled the codes and the codes are; P0700 U2105 U2106 U1800 Symptoms are that the truck seems to shift only on the mechanical shift points, somwhere around 2500 rpm. 2K views 1 reply 2 participants last post by davester Mar 7, 2017 1 Sep 19, 2015 · Went into a store today and came out and my truck would not start. any help? I think it has something to do with my FICM from my preliminary searches and everything. I thought it was just too cold for the truck to start. Check battery voltage and ground connections, inspect FICM harness for damage, and test relay function. As she sits, stock truck minus carter lift pump, she has 225ish psi on actual rail pressure. Ive been inspecting everything I can and it still just doesn’t seem to want to fire even After I installed the FICM it ran for about 10 seconds and died. Jan 23, 2018 · I have a code u1800 for no communication between ecm and ficm. I cannot locate corrective actions for the network errors. Here's the complete story: Bought the truck a while ago with a bad head gasket. Inspect the ECM for faults and ensure proper grounding. If you were in water, check to see if you injested water in the air filter and messed up the MAF. Oct 4, 2010 · a buddy has an 04 lb7. Truck is the one in my signature. Dec 26, 2014 · I cleared them and shut It off and when I started it back up I got codes p0102 p0370 u1800 have wiggles wires while truck is running and check spots for rubbing cant find anything and my truck is running just fine now has not missed a beat. But after I cleared them and attempted to start it again they don’t come back. Sep 9, 2008 · U1800 is a loss of communication somewhere in the circuit. Sep 9, 2008 · Come join the discussion about duramax engines, performance, builds, modifications, classifieds, troubleshooting, maintenance, and more! Explore Our Forums 6. Got about 14 MPGs and about half way home the check engine light came on. And the truck seemed to go into a wierd shift pattern. P0090 and u1800 came up, cleared it and is not coming back. Come join the discussion about modifications, towing, classifieds, troubleshooting, maintenance, and more! Apr 20, 2021 · I have my project running now and it is throwing some codes, I am a little confused is the 0090 code the fuel rail pressure sensor or the control valve? Thanks Oct 20, 2019 · Keep me in the loop with Chevy and GMC Duramax Diesel Forum news The U1800 code on an LB7 Duramax indicates a communication fault with the Fuel Injection Control Module (FICM). No short to voltage or ground either on both those circuits and the CAN circuits. ygmi20 aw5i nrbs bt3 7hc yle l8 wfhwfga aek hyqbtaot