guages, many problems, 1 cause?

[jabba1]

I'm disabled, living on a fixed income and just bought a 1988 S10 for $200. I realized it would have problems, but this one I just can't figure out. Some of the gauges either arn't working or are inaccurate.

speedometer - ok
ampmeter - ok
tach - always reads higher than actual
water temp - key off mid-range, on it immediatly pegs high
oil pressure - reads low
fuel guage always reads between 1/4 & 1/2 full
check eng soon - comes on after driving over 60 mph and stays on till restarted.

Have a feeling this could all be traced to one fault, but I can't seem to locate it. Cleaned all contacts and verified ground (I think I did this right). Anyone have any thoughts? Know some of the sensors are good because using my son's Snap-on code reader temp is okay as well as tach and water temp. Is there somplace they branch off from the test plug to another connector, beside the one on the cluster, that I'm not finding? Could all those individual gauges be bad? Don't really want to have to pay more for gauges than I did for the whole truck.

Although I have some mechanical ability, The meds I'm on are really effecting my thinking, so don't be afraid to point out the obvious,

Thanks, Jabba1

[Robert.H]

I know this is probably a dumb question but regarding the oil pressure, did you check the oil (is it Full)? as for the tach i had the same problem with an aftermarket tach it ended up being a bad ground. this may be the same problem with the temp to. as for where the grounds are located i'm not sure. I know this is probably no help at all but i'm almost certain youre dealing with a ground problem.

[Mikado14]

Find an AutoZone near you and they will read the code for free. You must have one if the light is on. After you have it, post it here and we will go from there.

[Fireplug]

Oil pressure the sending units are known to go bad. A quick oil pressure test will tell if its a true low pressure or a bad sending unit.
Same thing for the coolant temp sending unit.
Also the float in the gas tank not reading correct is also a common problem

[jabba1]

Well, I retrieved the codes using a Snap-on Analyser and it showed a soft code 32. It also read the coolant temp from 10 deg cent, cold to 62 deg warm (Gauge pegged at 260+ constant), It showed rpm at 950 while gauge read 2700 and both increased with pedal. On function test the service eng soon light flashed codes 12 and 32.

While the engine was warming up I hooked a new ground wire to the main dash ground point and touched it to the block, battery, ecm housing and any ground straps I saw with no change. Or should I have hooked one side to neg bat and probed the black leads on the different connectors I find?

BTW oil full with cleaning aditive in it.

Why would the analyser be able to show correct coolent and rpm if sending unit bad? I did see evidence the previous owner had been into the inst cluster as many plastic posts were broken. The manual shows an ecm ground on the back of the block, but I couldn't locate it.

If I were to need a new cluster were would you guys suggest? Junk yards near here don't allow you to remove parts yourself and therefore charge almost as much as new. What do you think of ebay?

Tomorrow I'm going to try to do voltage readings from the coolant sending unit and maybe check the oil sender for clogs as well.

TIA
Jabba

[Mikado14]

Originally Posted by jabba1

Well, I retrieved the codes using a Snap-on Analyser and it showed a soft code 32. It also read the coolant temp from 10 deg cent, cold to 62 deg warm (Gauge pegged at 260+ constant), It showed rpm at 950 while gauge read 2700 and both increased with pedal. On function test the service eng soon light flashed codes 12 and 32.

While the engine was warming up I hooked a new ground wire to the main dash ground point and touched it to the block, battery, ecm housing and any ground straps I saw with no change. Or should I have hooked one side to neg bat and probed the black leads on the different connectors I find?

BTW oil full with cleaning aditive in it.

Why would the analyser be able to show correct coolent and rpm if sending unit bad? I did see evidence the previous owner had been into the inst cluster as many plastic posts were broken. The manual shows an ecm ground on the back of the block, but I couldn't locate it.

If I were to need a new cluster were would you guys suggest? Junk yards near here don't allow you to remove parts yourself and therefore charge almost as much as new. What do you think of ebay?

Tomorrow I'm going to try to do voltage readings from the coolant sending unit and maybe check the oil sender for clogs as well.

TIA
Jabba

The SnapOn analyzer doesn't read the temperature from the same sender. It reads it from the ECT, different sender.

What Fireplug said is probably correct. Change out the temp sender and the oil pressure sender.

It also appears obvious that someone, as you said, has been into the cluster and who knows what. You more than likely are looking at more than one problem.

Code 32 is normally the EGR code, it also could be a Barometric pressure sensor failure. I would say, R+R the EGR and clean it, then disconnect the battery for a few minutes to reset the computor.

[OverBoardProject]

As for the insterment cluster there are several of us that either frequent affordable auto wrecks, or own parts trucks, unfortanatly my parts truck had the cluster taken apart, and I won't be near an auto wreck for about a month, but someone else might be able to help you out... and send it C.O.D. through UPS.

just ask with another thread, it can never hurt

[errol anthony]

i have a problem with my fuel gauge, it shows the correct reading only for a minunte after i switched on the ignition thereafter it goes to the full mark.i have replaced the tank sender unit but the problem stays the same

[jabba1]

I found out that I'm not getting the 5v ref voltage to the inst panel. The manual I have is for an 87 and mine is an 88 2.8l, and the wiring is definatley not the same. The fuse is good, but no voltage on it with key in any position. I took the battery out and removed and cleaned all the grounds again and since I couldn't find the block or engine ground I ran a cable from the chassis to the intake manifold. I guess that was a no-no as now the truck won't start. The pain is getting to me and I have to quit for now, but thought I'd ask if anyone had any new ideas? I don't have the funds to popcorn sender units. Since (for example) the temp gauge is reading +260 degrees even with the sender unplugged, it should be easy enough to read the resistance if someone could tell me what it shoud be. Starting to loose it with the pain,

TIA
Jabba

[OverBoardProject]

if your engine is like my 85 28.L it shoud have the - battery cable running right to one of the bolts holding the alternator bracket to the head. Mine is still carburated, so this might not apply to yours though. If it turns over with this setup the engine is grounded properly

[jabba1]

88-92 are more similar, I have the chiltons, but everything is so fuzzy on thier wiring diagrams you can't read them. I'll be trying to figure out what I did wrong tomorrow,
Thanx,
Jabba

[jabba1]

r&r inst panel, disconecting battery reset computer and truck again runs. Temp gauge read normal for about 3 secs then the check eng light came on and it shot back up to +260. Now have code 15....Although truck is running. Need to borrow a better vom to get resistance off coolant senser.

[Mikado14]

I don't know the resistance offhand for a cold sender. However, code 15 is for the coolant temperature sender - circuit fault or voltage high.